title: Symptoms of sleep disordered breathing and risk of cancer: a prospective cohort study.
abstract: OBJECTIVE
  Sleep disordered breathing (SDB) has been associated with oxidative stress, inflammation, and altered hormonal levels, all of which could affect the risk of cancer. The aim of the study is to examine if symptoms of SDB including snoring, breathing cessations, and daytime sleepiness affect the incidence of total cancer and subtypes of cancer.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  The third wave (1991-1993) of the Copenhagen City Heart Study.
  
  
  METHODS
  There were 8,783 men and women in whom cancer had not been previously diagnosed.
  
  
  RESULTS
  Participants answered questions about snoring and breathing cessations in 1991-1993, whereas information about daytime sleepiness based on the Epworth Sleepiness Scale was collected in a subset of the participants (n = 5,894) in 1998. First-time incidence of cancer was followed until December 2009 in a nationwide cancer register. We found no overall association between symptoms of SDB and incident cancer. Yet, in the small group with high daytime sleepiness, we observed a surprisingly higher cancer incidence (hazard ratio = 4.09; 95% CI 1.58-10.55) in persons younger than 50 years. We also found a higher risk of virus/immune-related cancers (2.73; 1.27-5.91) and alcohol-related cancers (4.92; 1.45-16.76) among persons with daytime sleepiness. More SDB symptoms were associated with a higher risk of smoking-related cancers (Ptrend: 0.04). Apart from these findings there were no clear associations between symptoms of sleep disordered breathing and cancer subtypes.
  
  
  CONCLUSIONS
  We found very limited evidence of relationship between symptoms of sleep disordered breathing and incidence of cancer.
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark ; Copenhagen Stress Research Center, Copenhagen, Denmark.
authors.forename: Anne Sofie
authors.initials: AS
authors.lastname: Christensen
authors.forename: Alice
authors.initials: A
authors.lastname: Clark
authors.forename: Paula
authors.initials: P
authors.lastname: Salo
authors.forename: Peter
authors.initials: P
authors.lastname: Nymann
authors.forename: Peter
authors.initials: P
authors.lastname: Lange
authors.forename: Eva
authors.initials: E
authors.lastname: Prescott
authors.forename: Naja Hulvej
authors.initials: NH
authors.lastname: Rod
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology / Q000209:etiology*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012119:Respiration; D012307:Risk Factors; D012891:Sleep Apnea Syndromes / Q000150:complications*; D012913:Snoring / Q000150:complications; D014851:Wakefulness; D055815:Young Adult
keywords: Cancer; cohort study; daytime sleepiness; impaired sleep; sleep disordered breathing